Comparison : 24bit/192KHz/stereo FLAC vs. APE, How can it be ? Options

[foorious]

Hi everybody,

I've just made a small comparison between Monkey's Audio 3.99 (Extra High Compression) and FLAC 1.21 (Compression level 8 ), using 24bit/192KHz/stereo files (the files were generated from a vinyl rip).

Of course I expected APE to perform slightly better than FLAC, like it usually does for 16bit/44KHz/stereo files (2-3%, maybe even 5%)... but I didn't really expect this !



Take a look at all the file sizes : we're talking about 20% difference here ! The total file size is 1,53 Go for APE vs. 1,88 Go for FLAC.

So I don't understand. I'm a genuine FLAC enthusiast (all my files are FLAC), but... how can it be ? Is there something wrong here ? Can we do something to improve all the FLAC file sizes ?

Thanks in advance for your explanation.

[TBeck]

Take a look at all the file sizes : we're talking about 20% difference here ! The total file size is 1,53 Go for APE vs. 1,88 Go for FLAC.

Not really surprising for me...

From earlier evaluations of some 44 Khz files i knew, that FLAC has some weaknesses when it has to deal with low passed files. Well, because 192 Khz audio recordings usually don't contain much frequencies above 20 Khz, they could also be considered as low passed. Therefore i expected to see FLAC perform worse on 192 KHz samples.

Out of interest i unlocked TAK support for 192 KHz files (the last official release only supports up to 96 KHz). Since i don't have any 192 KHz recordings i upsampled the 13 files of my 24-bit/96 KHz test corpus (Cooledit with maximum quality settings).

Results:

CODE

FLAC 1.2.1
  -8               46.20
  
Monkey's Audio 3.99
  High             38.09
  Extra            35.52
  Insane           35.76

OptimFrog 4.600ex
  --ExtraNew       29.98

TAK 1.0.4 (with 192 Khz support unlocked )
  -p0              45.15
  -p1              37.93
  -p3m             34.91
  
TAK 2.0 (Developer version)
  -p3m             31.94
  
TTA 3.4
  Default          39.41
    
WavPack 4.41
  -hhx3            44.84
  -hhx4            34.01
  -hhx6            33.40

Quite similar to your findings...

So I don't understand. I'm a genuine FLAC enthusiast (all my files are FLAC), but... how can it be ? Is there something wrong here ? Can we do something to improve all the FLAC file sizes ?

I think the resolution/accuracy of FLAC's predictor coefficients isn't sufficient to deal with such files. I don't know, if it's possible to increase the accuracy without breaking the FLAC format.

Thomas

edit: Results for Monkey's Audio added.
edit 2: Updated the results for TAK -p0 to -p2. Better compression because of a quick optimization of some parameter estimation in the encoder.
edit 3: Results for WavPack -hhx3 added.
edit 4: Results for WavPack -hhx4 and -hhx6 added.
edit 5: Results for TAK 2.0 (Alpha, unreleased!) added.
edit 6: Results for TTA added.
edit 7: Results for OptimFrog added. Results for TAK 2.0 updated.

This post has been edited by TBeck: Jul 31 2008, 12:57